syzbot

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: 	0-...!: (1 GPs behind) idle=1ae/1/0x4000000000000000 softirq=99435/99436 fqs=0 
rcu: 	Tasks blocked on level-0 rcu_node (CPUs 0-1): P4860/1:b..l
	(detected by 1, t=10502 jiffies, g=185985, q=15)
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 6565 Comm: syz-executor.1 Not tainted 5.12.0-rc7-next-20210415-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__lock_acquire+0x14c/0x5230 kernel/locking/lockdep.c:4805
Code: 89 d9 48 89 1c 24 48 c1 e9 03 0f b6 14 11 84 d2 74 09 80 fa 03 0f 8e e5 13 00 00 48 c7 c1 20 97 33 90 41 8b b4 24 f0 09 00 00 <48> ba 00 00 00 00 00 fc ff df 48 c1 e9 03 0f b6 0c 11 48 c7 c2 20
RSP: 0018:ffffc90000007b80 EFLAGS: 00000046
RAX: ffffffff8fe98100 RBX: ffff88807b5709f0 RCX: ffffffff90339720
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff888028f10308
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
R10: fffffbfff1b901c1 R11: 0000000000000000 R12: ffff88807b570000
R13: 0000000000000000 R14: ffff888028f10300 R15: 0000000000000000
FS:  00007f0b46f88700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000280 CR3: 0000000014fe0000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 lock_acquire kernel/locking/lockdep.c:5512 [inline]
 lock_acquire+0x1ab/0x740 kernel/locking/lockdep.c:5477
 __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
 _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
 spin_lock include/linux/spinlock.h:359 [inline]
 advance_sched+0x53/0x9a0 net/sched/sch_taprio.c:744
 __run_hrtimer kernel/time/hrtimer.c:1537 [inline]
 __hrtimer_run_queues+0x609/0xe50 kernel/time/hrtimer.c:1601
 hrtimer_interrupt+0x330/0xa00 kernel/time/hrtimer.c:1663
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1106
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632
RIP: 0010:__sanitizer_cov_trace_pc+0x59/0x60 kernel/kcov.c:205
Code: 74 2b 8b 82 18 15 00 00 83 f8 02 75 20 48 8b 8a 20 15 00 00 8b 92 1c 15 00 00 48 8b 01 48 83 c0 01 48 39 c2 76 07 48 89 34 c1 <48> 89 01 c3 0f 1f 00 41 55 41 54 49 89 fc 55 48 bd eb 83 b5 80 46
RSP: 0018:ffffc90018897a40 EFLAGS: 00000216
RAX: 00000000000000b5 RBX: ffff8880198b9020 RCX: ffffc900126aa000
RDX: 0000000000040000 RSI: ffffffff81aa73f1 RDI: ffff8880198b9c90
RBP: 0000000020000280 R08: 0000000021000000 R09: ffff88807b5704b8
R10: ffffffff81aa73be R11: 0000000000000000 R12: ffff8880198b9c60
R13: 0000000021000000 R14: dffffc0000000000 R15: ffff88802a7b3100
 find_vma+0xd1/0x180 mm/mmap.c:2320
 do_user_addr_fault+0x2d7/0x1210 arch/x86/mm/fault.c:1351
 handle_page_fault arch/x86/mm/fault.c:1475 [inline]
 exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1531
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:577
RIP: 0010:copy_user_enhanced_fast_string+0xe/0x40 arch/x86/lib/copy_user_64.S:206
Code: 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 1f 00 c3 0f 1f 80 00 00 00 00 0f 1f 00 83 fa 40 0f 82 70 ff ff ff 89 d1 <f3> a4 31 c0 0f 1f 00 c3 66 2e 0f 1f 84 00 00 00 00 00 89 d1 83 f8
RSP: 0018:ffffc90018897bc8 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000180 RCX: 0000000000000180
RDX: 0000000000000180 RSI: 0000000020000280 RDI: ffff888032a34800
RBP: ffff888032a34800 R08: 0000000000000001 R09: ffff888032a3497f
R10: ffffed100654692f R11: 0000000000000000 R12: 0000000020000400
R13: 0000000020000280 R14: 0000000000000000 R15: ffffc90018897db0
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:52 [inline]
 _copy_from_user+0xf4/0x180 lib/usercopy.c:16
 copy_from_user include/linux/uaccess.h:192 [inline]
 copy_iovec_from_user lib/iov_iter.c:1954 [inline]
 iovec_from_user lib/iov_iter.c:1989 [inline]
 iovec_from_user+0x242/0x3c0 lib/iov_iter.c:1964
 __import_iovec+0x65/0x500 lib/iov_iter.c:2007
 import_iovec+0x10c/0x150 lib/iov_iter.c:2072
 vfs_readv+0xbb/0x150 fs/read_write.c:919
 do_preadv fs/read_write.c:1013 [inline]
 __do_sys_preadv fs/read_write.c:1063 [inline]
 __se_sys_preadv fs/read_write.c:1058 [inline]
 __x64_sys_preadv+0x231/0x310 fs/read_write.c:1058
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0b46f88188 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000000000018 RSI: 0000000020000280 RDI: 0000000000000003
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000d9f R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffe719e4b8f R14: 00007f0b46f88300 R15: 0000000000022000
task:syz-executor.2  state:R  running task     stack:29336 pid: 6562 ppid:  8459 flags:0x00000000
Call Trace:
 context_switch kernel/sched/core.c:4329 [inline]
 __schedule+0x917/0x2170 kernel/sched/core.c:5079
 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:5536
 irqentry_exit_cond_resched kernel/entry/common.c:392 [inline]
 irqentry_exit_cond_resched kernel/entry/common.c:384 [inline]
 irqentry_exit+0x7a/0xa0 kernel/entry/common.c:428
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632
RIP: 0010:check_kcov_mode+0x31/0x40 kernel/kcov.c:175
Code: 89 c2 81 e2 00 01 00 00 a9 00 01 ff 00 74 10 31 c0 85 d2 74 15 8b 96 3c 15 00 00 85 d2 74 0b 8b 86 18 15 00 00 39 f8 0f 94 c0 <c3> 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 31 c0 65 8b 15 77 7f
RSP: 0018:ffffc900187d78e8 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffff8880900f1c80 RDI: 0000000000000003
RBP: ffffc900187d79b8 R08: 0000000000000002 R09: 0000000000000012
R10: ffffffff83eb3ecb R11: 000000000000003f R12: ffff8880110858c2
R13: dffffc0000000000 R14: 1ffff920030faf39 R15: 000000000000038b
 write_comp_data kernel/kcov.c:218 [inline]
 __sanitizer_cov_trace_const_cmp8+0x1d/0x70 kernel/kcov.c:291
 xa_is_node include/linux/xarray.h:1226 [inline]
 xas_load+0x5b/0x140 lib/xarray.c:235
 mapping_get_entry mm/filemap.c:1769 [inline]
 pagecache_get_page+0x161/0x1900 mm/filemap.c:1837
 find_get_page_flags include/linux/pagemap.h:357 [inline]
 __find_get_block_slow fs/buffer.c:202 [inline]
 __find_get_block fs/buffer.c:1370 [inline]
 __find_get_block+0x4ba/0xda0 fs/buffer.c:1364
 sb_find_get_block include/linux/buffer_head.h:340 [inline]
 recently_deleted fs/ext4/ialloc.c:686 [inline]
 find_inode_bit+0x230/0x580 fs/ext4/ialloc.c:728
 __ext4_new_inode+0xc4d/0x5620 fs/ext4/ialloc.c:1063
 ext4_symlink+0x489/0xd50 fs/ext4/namei.c:3444
 vfs_symlink fs/namei.c:4172 [inline]
 vfs_symlink+0x473/0x6a0 fs/namei.c:4157
 do_symlinkat+0x27a/0x300 fs/namei.c:4202
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x465d67
RSP: 002b:00007ffd9835fa38 EFLAGS: 00000202 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000465d67
RDX: 00007ffd9835fb23 RSI: 00000000004bfaa5 RDI: 00007ffd9835fb10
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffd9835f8d0
R10: 00007ffd9835f787 R11: 0000000000000202 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000001 R15: 00007ffd9835fb10
task:systemd-udevd   state:R  running task     stack:22728 pid: 4860 ppid:     1 flags:0x00000000
Call Trace:
 context_switch kernel/sched/core.c:4329 [inline]
 __schedule+0x917/0x2170 kernel/sched/core.c:5079
 preempt_schedule_notrace+0x5b/0xd0 kernel/sched/core.c:5318
 preempt_schedule_notrace_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:36
 rcu_read_unlock_sched_notrace include/linux/rcupdate.h:795 [inline]
 trace_lock_acquire include/trace/events/lock.h:13 [inline]
 lock_acquire+0x5a0/0x740 kernel/locking/lockdep.c:5483
 rcu_lock_acquire include/linux/rcupdate.h:267 [inline]
 rcu_read_lock include/linux/rcupdate.h:657 [inline]
 path_init+0x6ac/0x1910 fs/namei.c:2302
 path_lookupat+0x30/0x850 fs/namei.c:2411
 filename_lookup+0x1b1/0x570 fs/namei.c:2454
 user_path_at include/linux/namei.h:60 [inline]
 do_faccessat+0x127/0x850 fs/open.c:425
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f2dda3089c7
RSP: 002b:00007fffc0756b08 EFLAGS: 00000246 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 000055e443f51db0 RCX: 00007f2dda3089c7
RDX: 00746e657665752f RSI: 0000000000000000 RDI: 00007fffc0756b10
RBP: 00007fffc0756b90 R08: 000000000000c000 R09: 0000000000001010
R10: 00007f2dda5c6b58 R11: 0000000000000246 R12: 000055e4427b0856
R13: 000055e443f45840 R14: 00007fffc0756b10 R15: 000055e443f2ef50
rcu: rcu_preempt kthread starved for 10502 jiffies! g185985 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=1
rcu: 	Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt     state:R  running task     stack:29072 pid:   14 ppid:     2 flags:0x00004000
Call Trace:
 context_switch kernel/sched/core.c:4329 [inline]
 __schedule+0x917/0x2170 kernel/sched/core.c:5079
 schedule+0xcf/0x270 kernel/sched/core.c:5158
 schedule_timeout+0x14a/0x250 kernel/time/timer.c:1878
 rcu_gp_fqs_loop kernel/rcu/tree.c:1983 [inline]
 rcu_gp_kthread+0xd21/0x1960 kernel/rcu/tree.c:2156
 kthread+0x3b1/0x4a0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
rcu: Stack dump where RCU GP kthread last ran:
NMI backtrace for cpu 1
CPU: 1 PID: 6563 Comm: syz-executor.3 Not tainted 5.12.0-rc7-next-20210415-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:164 [inline]
 rcu_check_gp_kthread_starvation.cold+0x1cc/0x1d1 kernel/rcu/tree_stall.h:478
 print_other_cpu_stall kernel/rcu/tree_stall.h:583 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:708 [inline]
 rcu_pending kernel/rcu/tree.c:3889 [inline]
 rcu_sched_clock_irq+0x1d46/0x2080 kernel/rcu/tree.c:2628
 update_process_times+0x16d/0x200 kernel/time/timer.c:1782
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:226
 tick_sched_timer+0x1b0/0x2d0 kernel/time/tick-sched.c:1373
 __run_hrtimer kernel/time/hrtimer.c:1537 [inline]
 __hrtimer_run_queues+0x1c0/0xe50 kernel/time/hrtimer.c:1601
 hrtimer_interrupt+0x330/0xa00 kernel/time/hrtimer.c:1663
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1089 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1106
 sysvec_apic_timer_interrupt+0x8e/0xc0 arch/x86/kernel/apic/apic.c:1100
 </IRQ>
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632
RIP: 0010:csd_lock_wait kernel/smp.c:440 [inline]
RIP: 0010:smp_call_function_many_cond+0x452/0xc20 kernel/smp.c:967
Code: 0b 00 85 ed 74 4d 48 b8 00 00 00 00 00 fc ff df 4d 89 f4 4c 89 f5 49 c1 ec 03 83 e5 07 49 01 c4 83 c5 03 e8 f0 39 0b 00 f3 90 <41> 0f b6 04 24 40 38 c5 7c 08 84 c0 0f 85 33 06 00 00 8b 43 08 31
RSP: 0018:ffffc90018797cb0 EFLAGS: 00000246
RAX: 0000000000040000 RBX: ffff8880b9c3bba0 RCX: ffffc90010499000
RDX: 0000000000040000 RSI: ffffffff81693e50 RDI: 0000000000000003
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000001
R10: ffffffff81693e76 R11: 0000000000000000 R12: ffffed1017387775
R13: 0000000000000000 R14: ffff8880b9c3bba8 R15: 0000000000000001
 on_each_cpu_cond_mask+0x56/0xa0 kernel/smp.c:1133
 on_each_cpu include/linux/smp.h:71 [inline]
 clock_was_set+0x21/0x30 kernel/time/hrtimer.c:889
 do_settimeofday64 kernel/time/timekeeping.c:1327 [inline]
 do_settimeofday64+0x3dd/0x5c0 kernel/time/timekeeping.c:1293
 do_sys_settimeofday64 kernel/time/time.c:195 [inline]
 do_sys_settimeofday64+0x1de/0x260 kernel/time/time.c:169
 __do_sys_clock_settime kernel/time/posix-timers.c:1079 [inline]
 __se_sys_clock_settime kernel/time/posix-timers.c:1067 [inline]
 __x64_sys_clock_settime+0x1a1/0x280 kernel/time/posix-timers.c:1067
 do_syscall_64+0x3a/0xb0 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc62d0c0188 EFLAGS: 00000246 ORIG_RAX: 00000000000000e3
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000466459
RDX: 0000000000000000 RSI: 0000000020000400 RDI: 0000000000000000
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffc0dbf3dff R14: 00007fc62d0c0300 R15: 0000000000022000